Doe-eyed ... Katie Homes poses for photographers at the Bambi Awards in Germany in November 2007. Photograph: Action Press/Rex Features

Things aren't looking so good for Katie Holmes. She might be on the fast-track to Thetan Level VIII but her career is stalling. Having pulled out of the Batman sequel, The Dark Knight, she's seen it go on to earn a record-breaking $155m in its opening weekend.

Her next career move is a brave one: making her Broadway debut in a production of Arthur Miller's All My Sons. Despite her attachment, ticket sales have been sluggish with less than $1m worth of tickets sold and many of those to speculative booking agencies. Holmes' theatrical obituary seems already written.

What Katie does next will be a return to TV. As her haircut suggests, Holmes is following the lead of other celebrities in a rut. Britney got her first positive news stories in months for a brief turn on How I Met Your Mother this year, while Lindsay Lohan signed up to Ugly Betty to remind us there's more to her than an inability to leave a limo discreetly. Now Holmes is to appear in an episode of legal drama Eli Stone, which airs just a few days after her play opens.

A celebrity guest star in a sitcom is nothing new (hell, it sustained Will and Grace for an unnecessary eight seasons). It's so established, there are several Emmy categories for guest stars; this year the list includes Sarah Silverman (Monk) and Steve Buscemi (30 Rock). It is becoming more frequent though. Perhaps with a number of entertainment-set comedies around, such as Curb Your Enthusiasm, 30 Rock and Entourage, the sudden appearance of Jessica Alba or Ben Stiller doesn't seem quite as shoehorned in as Tina Turner singing in Ally McBeal's local did.

Actors like the guest role for a number of reasons. Apart from the publicity and attention, it's a chance to show another side. Matt Damon got to play it for laughs in Will and Grace while Ricky Gervais kept a straight face in Alias. Other actors are there to support their (then) spouses, like Brad Pitt in Friends or Julia Roberts in LA Law. It's also a rare opportunity to puncture public perceptions and for an actor to send themselves up, winningly done by Liza Minelli in Arrested Development and Ian McKellen in Extras, to quote a British example. For the programme itself, it can be a ratings-winner, as proved by How I Met Your Mother's Britney episode.

Often the best ones are the surprise ones, those not hyped to death like Britney's and Katie's. Stephen Colbert's agitated tourist in Curb Your Enthusiasm (Steve Coogan take note) or Johnny Cash voicing a coyote in The Simpsons. Still, even if Katie can't quite live up to this company with her cameo, it'll still be less cringeworthy than her husband's appearance on Oprah.